The Fish Composition of Phan Thiet Bay, Binh Thuan Province, Vietnam in Connection with Environmental Quality

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1 Interdisciplinary Studies on Environmental Chemistry Marine Environmental Modeling & Analysis, Eds., K. Omori, X. Guo, N. Yoshie, N. Fujii, I. C. Handoh, A. Isobe and S. Tanabe, pp by TERRAPUB, The Fish Composition of Phan Thiet Bay, Binh Thuan Province, Vietnam in Connection with Environmental Quality Nguyen Thanh NAM 1, Nguyen Xuan HUAN 1, Vu Trung TANG 1, Todd W. MILLER 2 and Koji OMORI 2 1 Faculty of Biology, Hanoi University of Science, Vietnam National University, Hanoi 334 Nguyen Trai Str., Hanoi, Vietnam 2 Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama , Japan (Received 30 October 2010; accepted 7 January 2011) Abstract In order to obtain data on the fish composition of Phan Thiet Bay, Binh Thuan Province, Vietnam, a total of 500 fish samples were collected by a trawl-boat at a towing speed of 10 km/h. A total 178 marine fish species representing 137 genera, 77 families and 17 orders were identified, and showed a high level of diversity at the order and family taxa level, of which the order Perciformes was the most dominant. On average, each order had 4.5 families, 8.1 genera and 10.5 species; each family had 1.8 genera and 2.3 species; and 7 orders (41.2%) had only one species. In fish fauna of Phan Thiet Bay, demersal fishes constituted a larger proportion of the community compared to pelagics (78.1% and 21.9% with the ratio of 3.6/1.0), 120 species (67.4%) were reefassociated fishes belonging to 54 families and 12 orders representative of typical reef fish families, and 78 species (43.8%) were estuarine fishes. With 95 species (53.4%) having economic value, Phan Thiet Bay plays an important role in local communities. However, increasing development from tourism, fishing and industrial activities has resulted in this area to be the highest in terms of anthropogenic load in the Southern Vietnam coastal zone. In future research we will analyze the fish community and trophic dynamics of Phan Thiet Bay food web using stable isotopes (δ 13 C and δ 15 N), and community structure analysis from catch data. This study will provide very basic but essential information that can then be used to propose solutions for sustainable development of fish resources and marine ecosystems, and environmental protection. Keywords: Phan Thiet Bay, fish composition, stable isotope, trophic level INTRODUCTION Phan Thiet Bay is recognized as one of the most productive fisheries of Vietnam, with capture fishery exceeding over 50 thousand tons/year, in which fish proportion is >50%. Phan Thiet Bay is also one of the major upwelling regions of the Vietnam East Sea. This area has a very important role for local communities in supplying food, employment, and in exporting sea food and other related products. 159

2 160 N. T. NAM et al. Fig. 1. The rapid decline of capture fish productivity and the slight change in gross production of Phan Thiet Bay in period However, increasing development from tourism, fishing and industrial activities has resulted in this area to be the highest in terms of anthropogenic load in the Southern Vietnam coastal zone. For example, the overabundance of small boats and overfishing in the nearshore area using destructive methods, and unregulated construction of tourism facilities that directly discharged untreated wastewater to the marine environment. As a result conditions of the marine environment have quickly declined, and which is reflected in declining fish catch over recent years (ton of fish per kw of boat): 0.8 ton/kw (year 2000), 0.6 ton/kw (year 2003) and 0.4 ton/kw (year 2005) (Fig. 1). Moreover, the species composition of fish and fishery status in Phan Thiet Bay has not been well documented, thus, it very difficult for implementing the management and wise use of marine fish resources, and in general marine resources. Therefore, we studied on the composition of fish and fishery status in Phan Thiet Bay, and to move towards establishing the assessment of trophic levels in Phan Thiet Bay and proposing solution in wise use of marine resources. MATERIALS AND METHODS Samples A total of 500 fish specimens were collected by a trawl-boat at a towing

3 Fish Composition of Phan Thiet Bay, Vietnam 161 Fig. 2. Sampling sites in Phan Thiet Bay in Sep., 2006 (PT-1, PT-2, PT-3) and in Oct., 2007 (PT- 4, PT-5, PT-6). speed of 10 km/h in Phan Thiet Bay from 14 to 20 September, 2006 and from 9 to 12 October, 2007 (Fig. 2). Sample preparation and analysis Fish samples were carefully fixed, photographed, and kept in 70% alcohol. All samples were transported to the laboratory for storage, and future analysis. The morphological analysis method was performed by using the fish morphological characteristics and comparison method. The identification guides of FAO (1999, 2001) and Nakabo (2002) were used to determine the scientific name of fish specimens. Fish specimens were classified and arranged composition of taxa following Eschmeyer (1998). In addition, literatures from FAO (1999, 2001) and some others in Vietnamese, the FISHBASE 2004 software and the website /fishbase.org/ were used to identify the habitat of fish fauna. Fishery status analysis During the fieldwork, we also collected information about the fishery status, including the published documents of local government, fishery companies and interviewed local peoples (older than 40 years). This information is very important for assessing and examining the fishery status and challenges of the fishery in this area.

4 162 N. T. NAM et al. Table 1. Proportion of taxa within 17 orders of fish collected in Phan Thiet Bay. No. Order Family Genus Species No. % No. % No. % 1 Carcharhiniformes Torpediniformes Rajiformes Myliobatiformes Anguilliformes Clupeiformes Siluriformes Aulopiformes Batrachoidiformes Lophiiformes Beloniformes Beryciformes Syngnathiformes Scorpaeniformes Perciformes Pleuronectiformes Tetraodontiformes Total RESULTS AND DISCUSSION Fish composition A total of 178 marine fish species belonging to 137 genera, 77 families and 17 orders were identified in Phan Thiet Bay (Table 1). Table 1 and Fig. 3 (A, B, C) show of all taxa collected the order Perciformes is predominant in terms of the number of family (54.5%), genus (61.3%) and species (66.3%) level. This is followed in prevalence by the order Tetraodontiformes and Pleuronectiformes. A total of seven orders (41.2%) have only one species. On average, each order has 4.5 families, 8.1 genera and 10.5 species. Table 2 shows that 51 families (66.2%) and 42 families (54.5%) have just one genus and one species, respectively; 14 families (18.2%) have two species; family Carangidae has the largest number of genera (11 genera - 8.0%) and species (16 species - 9.0%), followed by Lutjanidae with 6 genera and 10 species. On average, each family has 1.8 genera and 2.3 species. These results indicate a high level of diversity at the order and family taxa level of marine fish fauna in Phan Thiet Bay, the order Perciformes is predominant, which is similar to other marine fish fauna from other tropical areas. Fish composition analysis Of the total 178 fish species identified, 120 species (67.4%) were reef-

5 Fish Composition of Phan Thiet Bay, Vietnam 163 Fig. 3. Proportion of taxa within 17 orders of fish collected in Phan Thiet Bay. Fig. 4. Types and habitats of fish fauna in Phan Thiet Bay, A) types, B) habitats. associated fishes belonging to 54 families and 12 orders (Fig. 4B). In which, the number species were examined following the checklist of coral reef fishes of Vietnam (77 species), FAO (96 species) (Thi and Quan, 2005; FAO, 1999, 2001) and 53 species belong to both lists. Thus, this study added 43 species to the coral reef fish checklist of Vietnam. According to Choat and Bellwood (1991), typical reef fishes constitute three major taxa (and three main groups also): (1) the chaetodontid fishes, comprising the families Chaetodontidae and Pomacanthidae; (2) the acanthuroids, comprising the Acanthuridae, Siganidae, and Zanclidae; and (3) the labroids, comprising

6 164 N. T. NAM et al. Table 2. Summary of the number of fish genera and species appearing in families of Phan Thiet Bay. Number of genera appears in a family Total Number of families % (Family) Number of genera % (Genera) Number of species appears in a family Total Number of families % (Family) Number of species % (Species)

7 Fish Composition of Phan Thiet Bay, Vietnam 165 Fig. 5. The number of boats during period in Phan Thiet Bay. Scaridae, Pomacentridae, and Labridae. With the exception of Zanclidae, almost these families have representative species in Phan Thiet Bay, reflecting the this area is very important for development and conservation of reef fish biodiversity. Of the fish fauna identified from Phan Thiet Bay, demersal fishes were a substantially larger proportion (78.1%) compared to pelagic fishes (21.1%) (Fig. 4A). However, the pelagic fishes contain a larger proportion of the economically value species. There are 95 species (53.4% of total 178 species) have economic value (Fig. 4B). In which, a total of 69 species belonging to 29 families and 9 orders can be used for food, with 44 species (63.8%) are pelagic compared with 25 species (36.2%) of demersal fishes. Many of these species are highly value such as Spotted eagle ray (Aetobatus narinari), Serranidae spp., Indian mackerel (Rastrelliger kanagurta), Kawa kawa (Euthynnus affinis), and Narrow-barred (Scomberomorus commerson). In particular, Japanese scad (Decapterus maruadsi) and Shortfin scad (Decapterus macrosoma) have contributed to a high production (~10 4 tons/year) of capture fishery, and they are the main source for the producing fish sauce in Phan Thiet City. A total of 28 species of coral reef fishes (2 species can be used for food), can be used for the aquarium trade, representing 16 families and 4 orders. Many species in this group are very popular in the global trade of aquarium fish, such as Yellow boxfish (Ostracion cubicus), White-spotted puffer (Arothron hispidus),

8 166 N. T. NAM et al. Long-spine porcupinefish (Diodon holocanthus), Barred soapfish (Diploprion bifasciatum), Epinephelus spp., Pennant coralfish (Heniochus acuminatus), Redcoat (Sargocentron rubrum), and Plaintail turkeyfish (Pterois russelii). We also found 78 estuarine fish species (43.8%) representing 47 families and 11 orders (Fig. 4B). Of these, some proportions were also the reef-associated fishes. Challenges to the fishery In recent years, the increasing in number of small boats has becoming one of the largest problems for fishery management in Phan Thiet Bay (Fig. 5). Many of these boats are too small to venture far offshore, thus concentrating capture fisheries to the nearshore and potentially resulting in the over-harvesting of fishes. However, nearshore areas are typical rearing habitat for many juvenile stages of commercially important species to Phan Thiet Bay, thus making the intensive harvest from these areas as a form of growth overfishing. Together with overfishing, there has also increasing coastal development from tourism, industry, and associated discharge of nutrients and chemical pollutants, which has resulted in this area to be one of the highest in terms of anthropogenic load in the Southern Vietnam coastal zone. Discussion and future study All fish specimens collected from Phan Thiet Bay were typical tropical marine fish species, in which, reef-associated fishes made up a large proportion (67.4%). The coral reef systems are not only to maintain high biodiversity and genetic resources but also to provide high biological productivity, similar to that observed from upwelling regions or mangrove forests. It is well known that the coral reef ecosystems are very sensitive to natural disturbances and human activities. Almost coral reefs (96% in the total of continental shelf of the Eastern Sea of Vietnam) are unprotected and exposure to exploitation and environmental pollution (Burke et al., 2002). The Phan Thiet Bay area now has faced with similar problems in the marine environmental protection, and in wise use of the natural resource. Stable isotopes of carbon (δ 13 C) and nitrogen (δ 15 N) are commonly used in ecological trophic and tracer studies because they can provide a relative measure of an organism s trophic level (δ 15 N) and its source production (δ 13 C). In future study, we are using stable isotope analysis to examine trophic relationships and source production to fishes and invertebrates of Phan Thiet Bay, most of which are commercially important and exploited species. This research will provide the first trophic assessment and analysis of community structure of coastal Vietnam, which can be a starting point to assess environmental status and provide solutions for sustainable development of fish resources and marine ecosystems (e.g., coral reef), and environmental protection. Acknowledgments The authors are grateful to the fishermen in Phan Thiet Bay, Binh Thuan Province, Vietnam for help with sampling. This work was supported by TRIG A Project from Vietnam National University, Hanoi, Vietnam.

9 Fish Composition of Phan Thiet Bay, Vietnam 167 REFERENCES Burke, L., E. Selig and M. Spalding (2002): Reefs at Risk in Southeast Asia. World Resources Institute, Washington, D.C., 72 pp. Choat, J. H. and D. R. Bellwood (1991): Reef fishes: their history and evolution. p In The Ecology of Coral Reef Fishes, ed. by P. F. Sale, Academic Press, California. Eschmeyer, W. N. (1998): Catalog of Fishes. California Academy of Sciences, San Francisco, 2905 pp. FAO (1999, 2001): FAO Species Identification Guide for Fishery Purposes: The Living Marine Resources of the Western Central Pacific, Vol. 3, 4, 5, 6. FAO, Rome, 2822 pp. Nakabo, T. (2002): Fishes of Japan with Pictorial Keys to the Species. English edition, Tokai Univ. Press, Kanagawa, 1800 pp. Thi, N. N. and N. V. Quan (2005): Biodiversity and Living Resources of the Coral Reef Fishes in Vietnam Marine Water. Science and Technics Publishing House, Hanoi, 120 pp. N. T. Nam (